Steg K4.02 Review: What the Listing and the Manual Say
The Steg K4.02 is a four-channel amplifier from Steg's K series, listed as Class AB and rated 115 W x 4 RMS into 4 Ω, 210 W x 4 into 2 Ω and 420 W x 2 bridged. Its Indian MRP is ₹1,59,990. Steg's operation manual, reproduced online, gives a fuse, a cable size and current figures that our listing doesn't, but it also disagrees with the listing on supply voltage, weight and standby current. This review sets the two side by side and covers inputs, filters, heat and how the K4.02 compares. See it on our Steg K4.02 product page.
Quick summary
Listed as Class AB: 115 W x 4 at 4 Ω, 210 W x 4 at 2 Ω and 420 W x 2 bridged at 4 Ω. The manual text we read does not state the class.
The manual gives a 125 A fuse, a 34 mm² (2 AWG) supply cable for a 5 m run and a maximum current of 53.2 A. Our listing states none of these.
The listing and the manual differ on supply voltage, weight and standby current.
Inputs are RCA, with no speaker-level input described. We found no owner reviews of the K4.02.
Steg K4.02 specifications
Specification | Our listing | Steg manual (ManualMachine copy) |
|---|---|---|
Class | AB | Not stated in the text we read |
Power at 4 Ω (14.4 V) | 115 W x 4 | 115 W x 4 (technical data); a separate block gives 120 W x 4 at under 1% THD+N |
Power at 2 Ω | 210 W x 4 | 210 W x 4 |
Bridged at 4 Ω | 420 W x 2 | 420 W x 2 |
Minimum load | Not listed | 2 Ω stereo, 4 Ω bridged |
Supply voltage | 9 – 15 V DC | 10 – 16 V |
Input sensitivity | 0.2 – 5 V | 0.2 – 5.0 V |
Idle or standby current | Standby below 1.4 A | Idle 1.49 A; standby below 1 mA |
Maximum current (14.4 V) | Not listed | 53.2 A stereo at 4 Ω; 109 A bridged at 4 Ω |
Fuse | Not listed | 125 A |
Supply cable | Terminals take up to 35 mm² | 34 mm² (2 AWG) for a 5 m run |
Weight | 6.47 kg | 5.52 kg |
Dimensions (W x H x D) | 560 x 56 x 232 mm | Not clearly given (unlabelled 34 cm and 50 cm in the OCR text) |
The manual column comes from a reproduction of Steg's K4|01 and K4|02 operation manual on ManualMachine. It is OCR text with some garbled cells and covers both amplifiers, so treat its figures as read, not confirmed. Steg's own website could not be opened from our research session.
Power, current draw and fusing
The listing and the manual's technical data agree on the three power ratings, but a separate rating block in the same text lists 85 and 120 W x 4 at 4 Ω (under 1% THD+N) without naming a model. The manual adds a 2 Ω minimum load per channel and 4 Ω bridged, so a bridged pair needs a load of at least 4 Ω. Its test conditions are 14.4 V, 25 °C and a resistive load, with 0.04% distortion at 1 kHz and 90% of nominal power into 4 Ω, a damping factor above 1000 and 107 dB signal-to-noise (A-weighted).
The same text gives the maximum current as 53.2 A in stereo at 4 Ω and 109 A in bridged mono at 4 Ω, and recommends a 125 A fuse and a 34 mm² (2 AWG) supply cable for a 5 m run. Our listing says the terminals take cable up to 35 mm². These are maximum figures at full output, not what the amplifier draws at normal listening levels, but they set the fuse and cable you need to budget for. The listing also says the transistors are hand-selected and sorted into more than 100 categories with in-house measuring equipment.
Inputs, filters and the module question
The manual describes RCA stereo inputs in two sections, A and B, each with its own sensitivity control and stereo/mono selector. No speaker-level input is described, so a factory stereo without RCA outputs needs a line-output converter or a DSP first.
Our listing mentions only crossover and filter functions. The manual is more specific: a high-pass or low-pass filter per input section at 12 dB/oct, with the frequency set by an optional AQXM2 module (22 to 8500 Hz in 56 values) or an SW4FQ selector (60, 80, 100 or 120 Hz). Without a module the filter defaults to 22 Hz, and bass boost isn't mentioned in the text we read. A STEGLINK socket connects to a PC running MYSTEGMANAGER software. If you would rather set crossovers in a processor, DSP tuning is a service we offer.
What owners and reviewers say about the Steg K4.02
When we checked in October 2026, we found no owner reviews, retailer review pages or magazine tests of the K4.02 itself. Related items exist, and none describes this model. An old caraudio.com thread about Steg's K amplifiers names the K4.02 only in a price conversion; one poster calls the range overbuilt, another preferred its sound to Audison's, and several call Steg expensive. A 2006 autohifi test summary covers the older K4.01: 65 of 100 points, second of eight, praised for sound, compact size and power, with flexible filters only through modules. The EISA page for the newer K4.01 II is press text, not an opinion. If you run a K4.02, tell us how it behaves in your car.
K4.02 vs the QK200.4 and other Class AB amps
The other Steg Class AB four-channel amp we list is the Steg QK200.4 (₹1,39,990 MRP): 200 W x 4 at 4 Ω, 300 W at 2 Ω and 600 W x 2 bridged in 394 x 64 x 207 mm. It lists more power than the K4.02 on a longest side 166 mm shorter, at a ₹20,000 lower MRP. The Steg ST402 (₹54,990) lists 120 W x 4 in 440 mm without naming its class. Outside Steg, three Class AB amps in our store give a fair yardstick:
Zapco REF 150.4 (₹1,89,990 MRP): 150, 230 and 470 W (4 Ω, 2 Ω, bridged), 416 x 210 x 62 mm overall, balanced RCA inputs and a published 2 x 40 A fuse rating.
Zapco Z-150.4 II (₹1,19,990 MRP): 165, 275 and 550 W, 479 x 190 x 62 mm overall, with a full, high-pass and low-pass crossover and 0 to 12 dB bass boost.
Deaf Bonce MLA-4120 (₹28,990 MRP): 120, 150 and 300 W, RCA and high-level inputs, filters from 10 Hz to 12 kHz at 12 dB/oct, 395 x 216 x 50 mm.
At 4 Ω the K4.02 lists the lowest power of these six amps and, at 560 mm, the longest body.
Who should buy it, and who shouldn't
Consider the K4.02 if you want a Class AB four-channel Steg, have a surface that can take a 560 mm chassis, will fit the cable and fuse the manual specifies, and can feed it from RCA outputs or a DSP.
Look elsewhere if you need a speaker-level input, filters set without extra modules, or more power per channel. The QK200.4 and both Zapco amps list more, the QK200.4 and Z-150.4 II at lower MRPs.
Installation notes for Indian cars
Measure for 560 mm first. The manual says to fix the four feet to a surface able to bear the stress and gives no clearance or ventilation figures, so leave air around the chassis. It describes a fan whose speed follows temperature, and a closed boot in an Indian summer gets hot. Our listing gives 6.47 kg and the manual 5.52 kg, so check the weight before choosing a panel. Fit the fuse near the battery and size the cable to the manual. VA3 Car Studio in Ghaziabad offers professional installation.
Price and where to buy
The Steg K4.02 has an MRP of ₹1,59,990. VA3 Car Studio often sells below MRP, so check today's offer on the K4.02 product page. It is sold as a genuine Steg product.
The bottom line
The Steg K4.02 lists three clear power ratings, and its manual adds fuse, cable and current figures that our listing omits. At 4 Ω it lists the lowest power of the amps compared here, and we found no published test of it. Confirm the supply range, weight, fuse and filter modules, and make sure you can feed it RCA signals, before you buy.
Steg K4.02 FAQ
What fuse does the Steg K4.02 need?
The manual reproduced on ManualMachine gives a 125 A fuse and a 34 mm² (2 AWG) supply cable for a 5 m run. Our listing gives neither, and the manual text is OCR, so confirm against the printed manual.
Is the K4.02 a Class AB amplifier?
Our listing says Class AB. The manual text we read does not state the class, so treat it as the listing's description until Steg's printed manual confirms it.
Does the K4.02 have speaker-level inputs?
No speaker-level input is described in the manual we read. It has RCA stereo inputs in two sections, A and B, so a factory stereo without RCA outputs needs a line-output converter or a DSP.
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